Abstract��
When the thrust coefficients of fuel consumption were constant, the calculation formulas of optimal cruise states (including posture and airspeed) were presented for long-range and long-endurance, and the calculation formula of range and endurance were given when flight strategy held airspeed or posture uniform. The results show that variable posture and airspeed are needed for long-range flight and changeless posture and variable airspeed are needed for long-endurance flight. The example expresses that when the flight parameter is close to the optimal ones, either changeless posture or constant airspeed flight can highly approach long-range or long-endurance flight. When the thrust coefficients of fuel consumption changing with airspeed, the above questions were studied also and the main processes of calculation were given.